%求傳遞函數和卷積
z=[-3;-7]
p=[0;-1+2j;-1-2*j;-1;-1]
pause
k=6
g1=zpk(z,p,k)
pause
g=tf(g1)
pause
g4=tf(1,[1 1])
pause
g3=feedback(g1,g4,-1)
pause
g3=tf(g3)
pause
syms tao t positive		%把t定義為限定性符號變量 
pause
ut=sym('sin(3*t)*Heaviside(t-1)-Heaviside(t-2)')
pause
ht=t*exp(-2*t);
pause
yt=int(subs(ut,t,tao)*subs(ht,t,t-tao),tao,0,t);
pause
yt1=simple(yt) ; %合并
% ezplot(yt,[-2,2]);